Grilling devices which have vertical fireboxes for cooking food by radiant heat from the side, and which optionally include a horizontal firebox for cooking food from below, are known. For example, U.S. Pat. No. 4,089,258, which was issued to the same applicant (Berger), and the contents of which are incorporated herein by reference, describes a portable cooking unit having a gas-fired vertical firebox assembly that can be used alone or in combination with a gas-fired horizontal firebox.
The vertical firebox assembly described in the Berger patent comprises a radiant heat source in the form of a plurality of ceramic briquettes stacked in a vertical array and heated to radiant temperatures. In this arrangement, the heated briquettes are retained in the vertical array by abutment against a forward lattice or screen, and collectively provide a source of radiant heat having a relatively large radiating surface. However, there are several disadvantages in the use of ceramic briquettes, including a substantial "heat-up" period before a radiant temperature is achieved, absorption of heat by the retaining lattice which is between the briquettes and the cooking zone, the inconvenience and expense of handling and stacking the individual briquettes, the necessity of replacing thermally fractured or damaged briquettes, and the cost of the original and replacement briquettes.